Color and ascorbic acid variations in cabbage cooked by various methods.

Ascorbic acid (AsA) is an essential nutritional component and powerful antioxidant in vegetables, and in plants, AsA levels are regulated by light. AsA levels in the leaves of Chinese chive (Allium tuberosum Rottler ex Spr), a popular vegetable, are poorly understood. Thus, this study was performed to assess the influence of light on AsA biosynthesis in chive and select related genes (AtuGGP1 and AtuGME1); in addition, bioinformatic analyses and gene expression level assays were performed. The biological information obtained for AtuGGP1 and AtuGME1 was analysed with several tools, including NCBI, DNAMAN, and MEGA11. After different light treatments were performed, the Chive AsA content and AtuGGP1 and AtuGME1 expression levels were determined. These results suggest that 1) compared with natural light, continuous darkness inhibited AsA synthesis in chives. 2) The amino acid sequences of AtuGGP1 and AtuGME1 are very similar to those of other plants. 3) The trends observed for the expression levels of AtuGGP1 and AtuGME1 were consistent with the AsA content observed in chives. Hence, we speculated that light controls AsA biosynthesis in chives by regulating AtuGGP1 and AtuGME1 expression. This study provided impactful and informative evidence regarding the functions of GGP and GME in chives.

Ascorbic Acid↗

PubMed2006

Simultaneous voltammetric measurement of ascorbic acid, epinephrine and uric acid at a glassy carbon electrode modified with caffeic acid.

A stable electroactive thin film of poly(caffeic acid) has been deposited on the surface of a glassy carbon electrode by potentiostatic technique in an aqueous solution containing caffeic acid. Poly(caffeic acid) was used as a modified electrode for the detection of ascorbic acid (AA), epinephrine (EP), uric acid (UA) and their mixture by cyclic voltammetry. This modified electrode exhibits potent and persistent electron-mediating behavior followed by well-separated oxidation peaks towards AA, EP and UA with activation overpotential. For the ternary mixture containing AA, EP and UA, the three compounds can well separate from each other at the scan rate of 20 mVs(-1) with a potential difference of 156, 132 and 288 mV between AA and EP, EP and UA and AA and UA, respectively, which was large enough to determine AA, EP and UA individually and simultaneously. The catalytic peak current obtained, was linearly dependent on the AA, EP and UA concentrations in the range of 2.0 x 10(-5) to 1.0 x 10(-3) mol l(-1), 2.0 x 10(-6) to 8.0 x 10(-5) mol l(-1) and 5.0 x 10(-6) to 3.0 x 10(-4) mol l(-1), and the detection limits for AA, EP and UA were 7.0 x 10(-6), 2.0 x 10(-7) and 6.0 x 10(-7) mol l(-1), respectively. The modified electrode shows good sensitivity, selectivity and stability, and has been applied to the determination of EP in practical injection samples and that of EP, UA and AA simultaneously with satisfactory results.

Ascorbic Acid↗

PubMed2006

Characterization of peroxidase in buckwheat seed.

A peroxidase (POX)-containing fraction was purified from buckwheat seed. The POX consisted of two isozymes, POX I and POX II, that were purified 6.6- and 67.4-fold, respectively. Their molecular weights were estimated to be 46.1 kDa (POX I) and 58.1 kDa (POX II) by gel filtration. While POX I and II each oxidized quercetin, o-dianisidine, ascorbic acid and guaiacol, only POX II oxidized ABTS. Kinetic studies revealed that POX I and II had lower K(m) values for quercetin (0.071 and 0.028 mM), ABTS (0.016 mM for POX II) and ascorbic acid (0.043 and 0.029 mM) than for o-dianisidine (0.229 and 0.137 mM) and guaiacol (0.288 and 0 ). The optimum pHs of POX I and II for various substrates were almost the same, except for quercetin; pH 8.0 for POX I and pH 4.5 for II. Their optimal temperatures were 30 degrees C (POX I) and 10 degrees C (POX II), and POX I was more stable than POX II above 30 degrees C.

Ascorbic Acid↗